A solenoid valve of this type is known from the data sheet of the GAS Company. These so-called flush mounting valves shown there consist of a valve housing in which the magnet and a pull armature provided with valve elements are arranged. These valves can be screwed into a base plate which contains both supply and operating lines. The external arrangement of the supply and operating lines and the internal valve construction achieve the result that these valves are of very small size. For the connecting of electric connecting lines which are external to the valve housing, solder points or surfaces are arranged on the end side of the valve housing facing away from the installation side. The soldering on of the connecting lines is selected in this known valve in order to maintain the small shape of the entire valve.
This type of electric contacting is, however, difficult during installation. In the event that such valves are installed, for instance, in a valve battery, the cables which must be soldered on already before the installation of the valves interfere with the screwing in of the built-in valves. Not least of all, the danger of thereby breaking off the lines is very great. Another disadvantage is that, upon replacing a defective valve, the connecting lines have to be melted off.
Proceeding from this known prior art, the object of the invention is further to develop a solenoid valve of this type in such a manner that the electrical connection to the solenoid valve can be produced more easily, in which connection the solenoid valve as a whole should continue to be of small size.
This object is achieved in accordance with the present invention by providing a solenoid valve including valve housing with at least one electrically conductive contact track having the shape of a circular disc and which is insulated from the valve housing and electrically connected within the housing with the magnet, and a cup-shaped cover which can be pushed over the end of the valve housing provided with the contact track, said cover being provided on its bottom side with at least one contacting element which engages under spring action on the corresponding contact track and is electrically connected to electric lines outside the housing. In this way, the advantage is obtained that the electrical connection is obtained simply by placing the cover on the valve housing. The construction of the conductive contact tracks as circular discs has the advantage that, upon the corresponding arrangement of the contact elements, an electrical connection is made between connecting lines outside the housing and the lines leading to the magnet which are within the housing, the cover being turnable without eliminating the electrical connection produced between contacting element and contact track. The advantage which, in turn, results from this is that, particularly when the solenoid valve is constructed as built-in valve, twisting of the electric connecting lines is prevented upon the screwing of the valve into the base plate since the cover can turn with respect to the valve housing. As a further advantageous embodiment of the present invention, the valve housing and the cover are provided with circumferentially extending annular protruding and recessed formations which engage in complementary fashion into each other in the region in which the valve housing and the cover can be pushed on each other, said formations holding the cover on the valve housing in the direction of attachment. In this way, assurance is had in advantageously simple manner that upon the turning of the cover with respect to the valve housing, undesired loosening of the cover is prevented. As mentioned above, a further advantageous embodiment of the present invention, provides the valve housing with two concentrically arranged contact tracks having the shape of a circular disc and providing the cover correspondingly with two spring-action contacting elements. By the concentric arrangement of the contact tracks, an unambiguously associated contacting via the correspondingly arranged contact elements is provided in each position of rotation of the cover on the valve housing. In a further preferred embodiment of the present invention, the valve housing is provided on the end side bearing the contact tracks with a centrally arranged vent opening and the cover is provided at the corresponding location with a passage way for maintaining the vent opening. Thus, the venting of the valve is continued to be assured in a simple manner. In combination with this, it is of advantage that in a further embodiment of the present invention the cover is provided with an annular seal, extending concentrically to the passage way for keeping the pressure fluid away from the contact tracks and contacting elements. A depositing of oil dirt or dust which can impair the electric contact between contact track and contacting element is thus prevented. As further embodiment of the present invention, the passage way is provided with an internal thread and the cover has, in the region of the passage way on the outer end side, a hexagonally shaped outer construction for the engagement of a wrench. The internal thread arranged in the passage way thus permits the connecting of an external vent line or, for instance, the screwing in of a vent dampening. In this connection, the hexagonal construction arranged on the outer end side proves advantageous since, by means of a wrench, the cover can be held in place for the screwing of a corresponding device into the passage way. As a further advantageous embodiment of the present invention, an axially displaceable ring is arranged on the outer circumference of the cover for the clamping of the cover to the valve housing. The cover is provided with a circumferential bead on its outer circumference, and the ring on the inner surface is provided with an annularly extending correspondingly concave groove in such a manner that, when the ring is pushed onto the correspondingly shaped bead, the stop position for the clamping of the cover onto the valve housing is present. Thus, as a whole, the mechanical securing of the cover on the valve housing against axial lifting off is obtained in an advantageously simple manner. As a further embodiment, the cover is provided on the bottom side with an opening for the passage of the external electric connecting lines and the cover is provided in this region with a strain relief for the clamping of the connecting lines. In this way, the connecting lines are secured against being unintentionally pulled out. In the last advantageous embodiment of the present invention, a quenching diode is arranged within the cover, it being electrically connected to the contacting elements. This quenching diode serves to short-circuit the induction peaks produced within the valve after connection or disconnection by the inductance of the magnet coil, thus eliminating them.